Systems and methods for measuring high-intensity light beams

Abstract

Systems and methods for measuring an intensity characteristic of a light beam are disclosed. The methods include directing the light beam into a prism assembly that includes a thin prism sandwiched by two transparent plates, and reflecting a portion of the light beam by total-internal-reflection surface to an integrating sphere while transmitting the remaining portion of the light beam through the two transparent plates to a beam dump. The method also includes detecting light captured by the integrating sphere and determining the intensity characteristic from the detected light.

What is claimed is: 
     
       1. A method of measuring an intensity characteristic of a light beam, comprising:
 directing the light beam into a prism assembly that includes a thin prism sandwiched by two transparent plates, wherein the thin prism has a width d and a total-internal-reflecting (TIR) surface having an area; 
 reflecting a portion of the light beam by the TIR surface to an integrating sphere while transmitting the remaining portion of the light beam through the two transparent plates to a beam dump; 
 detecting a portion of the light captured by the integrating sphere; and 
 determining an intensity characteristic of the light beam from the detected light. 
 
     
     
       2. The method of  claim 1 , wherein detecting the portion of the light captured by the integrating sphere measures an amount of optical power, and further including determining an intensity by dividing the measured amount of optical power by the area of the TIR surface. 
     
     
       3. The method according to  claim 1 , further comprising repeating the acts therein to measure an intensity for different sections of the light beam to determine an intensity profile for the light beam. 
     
     
       4. The method according to  claim 3 , further comprising translating the light beam relative to the prism assembly to measure the intensity for the different sections of the light beam. 
     
     
       5. The method according to  claim 1 , wherein the light beam comprises a line-forming beam that forms a line image. 
     
     
       6. The method according to  claim 1 , wherein the width d of the TIR prism is in the range from 0.05 mm to 1 mm. 
     
     
       7. The method according to  claim 1 , wherein the transparent plates have a substantially pentagonal shape and the thin prism has a substantially trapezoidal shape. 
     
     
       8. The method according to  claim 1 , wherein the thin prism has input and output surfaces configured so that the light beam passes through the input surface at substantially a right angle and the reflected portion of the light beam passes through the output surface at substantially a right angle. 
     
     
       9. The method according to  claim 8 , wherein the input and output surfaces of the thin prism are coated with an anti-reflection coating. 
     
     
       10. The method according to  claim 1 , wherein the thin prism and transparent plates have light-transmitting surfaces and wherein the light-transmitting surfaces are coated with an anti-reflection coating. 
     
     
       11. The method according to  claim 1 , wherein directing the light beam into a prism assembly includes focusing the light beam so that it substantially focuses at the TIR surface. 
     
     
       12. The method according to  claim 1 , wherein the light beam has an amount of optical power between 10 W and 5 kW. 
     
     
       13. A system for measuring an intensity characteristic of a light beam, comprising:
 a prism assembly arranged to receive the light beam at an input side, the prism assembly including a thin prism sandwiched by two transparent plates, wherein the thin prism has a width d and a total-internal-reflecting (TIR) surface, wherein the TIR surface reflects a portion of the light beam, thereby defining an unreflected portion of the light beam; 
 an integrating sphere arranged adjacent a first output side of the prism assembly to receive the reflected portion of the light beam; 
 a beam dump arranged adjacent a second output side of the prism assembly and arranged to receive the unreflected portion of the light beam; 
 a photodetector operably arranged relative to the integrating sphere and adapted to measuring an amount of optical power received by the integrating sphere and generating an electrical detector signal representative of the measured amount of optical power; and 
 a processor electrically connected to the photodetector and that includes instructions embodied in a computer-readable medium that cause the processor to determine the intensity characteristic of the reflected portion of the light beam. 
 
     
     
       14. The system according to  claim 13 , wherein the TIR surface has an area and wherein the processor determines an intensity by dividing the measured amount of optical power by the TIR surface area. 
     
     
       15. The system according to  claim 13 , wherein the width d of the TIR prism is in the range from 0.05 mm to 1 mm. 
     
     
       16. The system according to  claim 13 , further comprising a movable stage that movably supports the prism assembly relative to the light beam. 
     
     
       17. The system according to  claim 13 , wherein the transparent plates have a substantially pentagonal shape and the thin prism has a substantially trapezoidal shape. 
     
     
       18. The system according to  claim 13 , wherein the thin prism has input and output surfaces configured so that the light beam passes through the input surface at substantially a right angle and the reflected portion of the light beam passes through the output surface at substantially a right angle. 
     
     
       19. The system according to  claim 13 , wherein the thin prism and transparent plates have light-transmitting surfaces and wherein the light-transmitting surfaces are coated with an anti-reflection coating. 
     
     
       20. The system according to  claim 13 , wherein the light beam is substantially focused at the TIR surface. 
     
     
       21. The system according to  claim 13 , further comprising means for scanning the light beam relative to the prism assembly. 
     
     
       22. The system according to  claim 12 , wherein the light beam has an amount of optical power between 10 W and 5 kW.